反应，如何模拟单元测试的用户输入？

Question

我一直在尝试单元测试一个反应组件，它接受用户输入。更具体地说，我试图在反应组件中测试onChange函数。然而，我似乎无法设置输入值，我尝试了在互联网上建议的几种不同的方式，但似乎没有任何工作。下面是我试图测试的组件。

class Input extends Component { 
    constructor(props) { 
    super(props); 
    this.state = {value: ''}; 
    this.handleChange = this.handleChange.bind(this); 
    } 

    handleChange(event) { 
    /* Check if max length has been set. If max length has been 
    set make sure the user input is less than max Length, otherwise 
    return before updating the text string. */ 
    if(this.props.maxLength) { 
     if(event.target.value.length > this.props.maxLength) { 
     return; 
     } 
    } 
    this.setState({ value: event.target.value }); 
    } 

    render() { 
    const { disabled, label, maxLength, multiline, type, value, ...others} = this.props; 
    const theme = themeable(others.theme); 

    let inputClassName = classNames({ 
     "input": type !== 'checkbox', 
     "checkbox": type == 'checkbox', 
     disabled, 
     multiline, 
     value, 
     [`${this.props.className}`]: !!this.props.className 
    }); 

    return (
     <div {...theme(1, 'container')}> 
     {this.props.label ? <label htmlFor={this.props.htmlFor} {...theme(2, 'label')}>{label}</label> : null} 
      <input value={this.state.value} {...theme(3, ...inputClassName)} onChange={this.handleChange} type={type} /> 
     </div> 
    ); 
    } 
} 

我发现这个问题：https://github.com/airbnb/enzyme/issues/76，并试图向底部的建议，我不断收到未定义或空字符串。我尝试了levibuzolic使用酶的模拟变化的建议，这可以在下面看到。然而，这只是返回AssertionError: expected '' to equal 'abcdefghij'

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    result.find('input').simulate('change', {target: {value: 'abcdefghijk'}}); 
    expect(result.state().value).to.equal("abcdefghij"); 
}); 

然后我试图takkyuuplayer的建议，这也是下面。这也将失败，并AssertionError: expected '' to equal 'abcdefghij'

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    result.find('input').node.value = 'abcdefghijk'; 
    expect(result.state().value).to.equal("abcdefghij"); 
    }); 

我发现这篇文章：https://medium.com/javascript-inside/testing-in-react-getting-off-the-ground-5f569f3088a#.f4gcjbaak和尝试他们的方式也失败了。

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    let input = result.find('input'); 
    input.get(0).value = 'abcdefghijk'; 
    input.simulate('change'); 
    expect(result.state().value).to.equal("abcdefghij"); 
    }); 

最后我试图使用由Simulating text entry with reactJs TestUtils所建议的反应测试utils的，下面是我尝试的代码，但是这并没有与错误消息：TypeError: Cannot read property '__reactInternalInstance$z78dboxwwtrznrmuut6wjc3di' of undefined

it('Make sure inputted text is shorter than max length', function() { 
    const result = mount(<Input maxLength={10}></Input>); 
    let input = result.find('input'); 
    TestUtils.Simulate.change(input, { target: { value: 'abcdefghijk' } }); 
    expect(result.state().value).to.equal("abcdefghij"); 
    }); 

那么如何一个模拟用户输入所以他们可以测试onChange函数？

Answer 1

您的输入组件中似乎有一个错误。当event.target.value.length > this.props.maxLength您从未设置实际状态，将state.value作为''。你似乎认为它已被设置为该值，但被截断为maxLength。你需要补充的是自己：

handleChange(event) { 
    /* Check if max length has been set. If max length has been 
    set make sure the user input is less than max Length, otherwise 
    return before updating the text string. */ 
    if (this.props.maxLength) { 
    if (event.target.value.length > this.props.maxLength) { 
     // ** Truncate value to maxLength 
     this.setState({ value: event.target.value.substr(0, this.props.maxLength) }); 
     return; 
    } 
    } 
    this.setState({ value: event.target.value }); 
} 

...那么，下面的测试工作，并通过：

it('Make sure inputted text is shorter than max length',() => { 
    const result = mount(<Input maxLength={10}></Input>); 
    result.find('input').simulate('change', { target: { value: '1234567890!!!' } }); 
    expect(result.state().value).to.equal("1234567890"); 
});